Last year I rebuilt my AC system. Everything was new except the evaporator core and the pressure switch which I removed from the original accumulator and placed on the new accumulator.

I also flushed out the evaporator core using the AC flush liquid with the compressor air. I put it all together, vacuumed it for 2 hours, let it sit for another hour to check for leaks. Nothing changed on the gauges so I figured no leaks. I then proceeded to fill the system with the amount of R134 specified on the sticker on top of the radiator. The system blew cold again - not as cold as I expected but down to 55 degrees. I was happy.

Then in the winter I used the AC to defog the windows and noticed the compressor cycling on and off quickly as if the system had leaked and was low on R134.

So last weekend I test the AC again and it is running normal again. I put the gauges on and all the readings are within the range specified by the FSM.

I did notice the high pressure line schrader valve leaked a little when I disconnected the gauge from it, I will be replacing it.

Could the pressure switch malfunction randomly? Should I just replace it when I do the valve?

Thanks.

 

Ac compressor will cycle on and off in defrost mode .

 

Thanks, freegdr.